This depends on the region you live. Here in SoCal, there is no need for AWD. With all the BMW dealers we have here in LA, I bet it's difficult to find a 535xi or 550xi. There's just not much need or demand for AWD here. I personally think RWD is much more fun to drive as permitted by the weather here. RWD also means less weight and slightly better MPG. One thing I hated about MB was why they only offer the E550 as AWD for MY13. Seems like MB is really pushing their 4 Matic.

I just wish they offered RWD for the X5, but that's my wife's car. That's just me.

With 400+hp cars, I would prefer AWD no matter where I lived. To me, it is absolutely no fun to spin my tires in the rain or to squeal my tires when aggressively launching from a light.